Sprinkling irrigation and micro irrigation are two common examples of employing advanced technology in water conservation and high efficiency irrigation. In China, only 2% of the total irrigation area benefits from this technology whereas the developed countries apply this technology to over 80% of their total irrigated areas. The need for China's agriculture to implement water conservation technology is quite obvious, especially in regions that have a shortage of water resources. However, sprinkling irrigation has some problems, such as blind spots that do not get irrigated, susceptibility to the influence of wind velocity and direction, loss of water by evaporation, and insufficient supply of water to the deep soil layers. In micro irrigation systems, the water outlets are so small that they easily get clogged with mineral or organic particles in the water. Water pressure in the feeding lines is often affected by the terrain, causing an uneven supply of water in the system and thus reducing the effectiveness of irrigation.
In the conventional technology, there is a system called “Underground Infiltration Irrigation Device with Water Replenishment and Storage Capabilities” (Patent Application No. 00268186.2), which consists of a water permeable storage container, a lid, a water supply pipe, a water-feeding and air-relieving pipe, and a plug. The lid is installed on the container. The water-feeding and air-relieving pipe is connected to the lid at one end and to the water supply pipe at the other end. The water-feeding and air-relieving pipe contains two parallel hoses inside: one for water feeding and the other for air relieving. When the container is filled with water, the water replenishment process is halted. Then, it is necessary to disconnect the water supply pipe from the water-feeding and air-relieving pipe and also insert a plug to stop the opening of the latter pipe. That process is very time-consuming and labor-intensive. In addition, the water supply pipe takes up some space that might be used for growing plants. What's more, the water supply pipe is not easy to use, thus adversely affecting the irrigation efficiency.
Another example of the conventional technology is a small irrigation device called “Root Infiltration Irrigation Cup” (Patent Application No. 99246573.7), which consists mainly of a cylindrical cup of a specific volume. The said cup has 1-4 groups of infiltration holes on the side walls of the bottom section. Each group has 1-4 directional holes, which are covered with a screen made of non-woven cloth, embedded steel wool and sand filtration material or stainless steel composite filtration meshes. The cup has a lid with a water feeding pipe attached and an air relieving hole in it. Once the lid is placed over the upper opening of the cylindrical cup, a water supply pipe is connected to the water feeding pipe. The cup is buried near the roots of the plant, with the lid a little over the ground. In actual application, water has to be transported to each individual cup. Liquid fertilizers may be mixed with water so that irrigation and fertilizer application are achieved at the same time. This “Root Infiltration Irrigation Cup” also has problems such as the need to feed water to each individual cup, the occupation of space that might be used for growing plants, and the difficulty with maintenance.
All in all, the applications of the conventional technology discussed above have the common problems of time-consuming and labor-intensive operation, high maintenance cost, short life time, low recovery rate of used materials, frequent assembly and disassembly requirements, possibility of damage to plants, ineffective use of water resources, high evaporation loss rate, low irrigation efficiency, occupation of plant growth space, and adverse effect on the natural growth of plants.